You never expected that this could happen.
The body you have been given, the world you were making a home in, the battles you've conquered and the friends you made along the way.
Where will they all go?
You never expected that Kris would go this far.
At first you weren't concerned. During the day you both went to school. You both talked to everyone in town. You both ate your mother's pies, even the snail ones. As someone born without their own vessel, you felt alive and finally in control. You had choices to make and hoped those decisions would be fruitful. You would never make them do anything irredeemable, no. You just wanted to have fun and perhaps save the world. None of those choices mattered. Kris, at first, was a device for you. A face with arms and legs to do your actions. You knew next to nothing about Kris; they never spoke to you and you shamefully never thought to ask. Yet slowly but surely, you learned about them through the monsters you conversed with. They played piano, they were a trouble maker, and they very much loved their older brother, Asriel. The more you learned about who Kris used to be, the more guilt you carried in yourself. But you couldn't give them up yet. In your perspective, you were placed inside Kris for a reason..
The Dark World opened doors to a greater purpose. You, Susie, and Ralsei would close Dark Fountains, world after world, save after save, to maintain the balance of all life. Your first trip to the Dark World is when Kris first retaliated. They tore you from their chest and slammed you into a bird cage with pure animosity. You were horrified. This wasn't supposed to happen. However even though they never spoke to you, words weren't necessary. You understood they felt trapped and a bystander in their own life, as you watched them behind the cage's bars. Without you, Kris could not move to their full capability and appeared almost crippled. Still they wore the biggest, spine-chilling smile as they held that knife. Passing out from shock, you did not see what happened afterwards. The third time they ripped you from their body, you were more prepared. Kris had again retrieved their knife, and shortly after stabbed the living room floor. A blinding, white flash of light and then…a thick, menacing black cloud filled the room. You felt an uneasy mixture of confusion and betrayal. This was not in the prophecy. You were supposed to be their SOUL, the culmination of their very being. What was your willing vessel doing?
In silent horror you understood that you had everything backwards. In this very moment, you could not stop them. You had no body. You had no voice. You needed Kris more than they needed you. In overwhelming gratitude you found all too late, you realized you could not have accomplished anything in your fleeting life without Kris. You would have remained floating in a listless void. You wouldn't have friends to see after school. You wouldn't have a caring mother to wake you up every morning. You wouldn't anticipate what the next day would bring because every day would be excruciatingly the same. Is this what taking everything for granted meant?
When Kris returned to the couch and crushed you back inside their chest, you chose to FIGHT. Acting would be futile, you couldn't blame them for not trusting you. Using your soul power, you caused Kris to experience something similar to a heart attack. The constant pang and tightness in their chest was akin to unbreakable chains, a reminder that they were yours and you were not going anywhere. Kris bit their lip to stifle their screams, hard enough that blood trickled down their chin. Having enough sense to not battle where Toriel and Susie slept, they struggled up the stairs and into their bedroom. They rammed the door shut and locked it. Kris soon dropped to their knees and hands, sweating bullets and choking on their own breath. This was it. This was the end. You would be able to stop this attack once Kris submits to you. They had to stop resisting you.
But Kris was a human. They possessed a valuable trait that you lacked. Alarmed, you felt burned by their inner strength spreading around you. You could no longer attack as powerful as you have before. Kris turned away from the door and crawled to the middle of the room. Still, they wouldn't speak.
Again, they brandished their unsettling grin
As they unsheathed their horrid knife
And sunk it directly into their sternum
Killing off your soul
Briefly regaining their stolen life
Before the last Dark Fountain swallowed you both whole.